UK Prime Minister Boris Johnson says he will not make Christmas gatherings illegal after the UK’s four nations “unanimously” agreed not to scrap their plans entirely.
Mr Johnson is under pressure from doctors to tighten coronavirus restrictions over the five days around Christmas.
The current rules allow up to three households to meet from December 23 to 27.
On the day pubs and restaurants were forced to close again in London, Mr Johnson said the easing of restrictions would go ahead.
“We don't want to criminalise people's long-laid plans," he told Parliament.
But Mr Johnson said that people should exercise “personal responsibility” around the vulnerable.
"By being sensible and cautious, not by imposing endless lockdowns or cancelling Christmas ... that is the way we will continue to work together to keep this virus under control, to defeat it and take the country forward," he said.
Caution and sense were not the watch words of the night in London on Tuesday. This video shows the raucous scenes.
Starmer is Scrooge, says Johnson
Mr Johnson accused Labour leader Sir Keir Starmer, who called on the prime minister to review the rules, of wanting to "cancel Christmas".
Meanwhile, Wales tightened its restrictions, now allowing only two households to mix over the five days.
Scottish First Minister Nicola Sturgeon said it was her recommendation that people should spend Christmas "in your own home with your own household".
The loosened restrictions come amid surging infection rates and the discovery of a new coronavirus strain.
Millions more were placed in the toughest restrictions on Wednesday after London moved to Tier 3.
About 61 per cent of England’s population is now living under those harsh restrictions.
Earlier, Housing Secretary Robert Jenrick said the government would tell Britons to use their common sense at Christmas.
“The law remains unchanged," Mr Jenrick told BBC Radio 4.
"We have and will be providing guidance, and that guidance will reflect that cases are rising. We will be asking people to make an informed judgment.
“That’s why it’s better to treat this as a personal judgment issue, to weigh up the risk to loved ones.”
He said that people might choose to ignore a ban on meeting over Christmas and that it was better for it to be regulated in some way.
“It's not for the government to tell people exactly how to handle this situation,” Mr Jenrick said.
Labour leader warns of grave risk
The government is still expected to set out stronger advice on how to keep elderly relatives safe.
This could include asking people to isolate themselves and reduce social contacts before joining other households.
"The choice is a grim one," Welsh First Minister Mark Drakeford said.
But Mr Drakeford said the current plans were a "hard-won agreement" that he would not put aside lightly.
The UK recorded another 18,450 cases on Tuesday, bringing the seven-day tally to 137,876, a 29 per cent increase on the week before.
But the number of deaths has fallen by about 4 per cent over the same period. Another 506 fatalities were recorded on Tuesday.
In a rare joint editorial, the British Medical Journal and the Health Service Journal on Tuesday said the government's relaxation of social distancing rules over the holiday could bring a third wave of coronavirus.
Mr Starmer earlier said the government had “lost control of infections”, putting the economy and National Health Service at “grave risk” in the new year.